Valve arrangement for halting reversible rams to prevent overstroking thereof



B. D. ASHBAUGH VALVE ARRANGEMENT FOR HAL'IING REVERSIBLE RAMS March 2, 1948 TO PREVENT OVERSTROKING THEREOF FiledMarch 6, 1944 x H G U A mm Wu E I muxz 1D A N R E B- m: w F y flw v. w

latented Mar. 2, 1948 v I 1 VALVE ARRANGEMENT FOR HALTING RE- VERSIBLE RAMS TO PREVENT OVER,- STROKING THEREOF Bernard D. Ashbaugh, Mount Gilead, Ohio, as-

ElCE- signor to H-P-M- Development Corporation, Wilmington, Del., a corporation oi Delaware Application March 6, 1944, Serial No. 525,193

3 Claims.

This invention relates to fluid operable systems and; particularly, to fluid operable control (Cl. Bil -52) systems for use in connection with the control of a hydraulic motor.

2 eludes control cylinder and piston assemblies responsive to predetermined pressures for moving the pump toward and into neutral or no delivery position.

In hydraulic presses which include a recipro- I Accordin t h Pr n invention a Valve cating ram, it. is desirable that means be proprovid d W hpin response to apredeteimmed vided for preventing the over-stroking of the travel of the ,reciprocatingram, closes on the said ram. This is desirable in order to prevent exhaust passage from the ram a thereby causes the ram from bottoming against thepacking or 'apressure to be built up th r n. h Pressure other parts of the press or cylinder which are 10 is conducted to one of the aforementioned connot designed to support the thrust of the said trol cylinder piston assemblies and is effective to ram. Also, in many instances it is necessary to m e h p p to neutral. provide a means to stop the ram at a predetermined point during or immediately subsequent L *xP-petguedd'escnptlon to the working strolre thereof so as to prevent 16 Referring to the drawings in detail and, parthe damaging of expensive blanking i firming ticularly, Figure '1', there is shown a fluid operable diesmotor means comprising a cylin r h v ns Hitherto it has been customary to provide reciprocably t t rein a differentialpositi te means such as blocks which the plunger ll having an advancing area I! and a ram or platen engages at the aforementioned go retracting n,

predetermined point of travel. Such an'arrangesource of pressure h as th pump is m n h s t dis v of unduly stressing provided for supplying fluid through the conduit the mechanical parts of the press as well as .4. valve n t th conduits i8 and I! overloading'the hydraulic circuit. Also considand th m t t erees I: and I3 thereby to erable shock may be created by the sudden haltg t 'th pm II, Th ump l5 draws ing or the press ram or platen against'a pos t v fluid from the reservoir 20 through a conduit and unyielding s means such as a blockzi. while the 4-way valve 11- exhausts fluid Accordingly. it is an object Of th s invention through the conduit 22 back to the reservoir 2|. to provide a means for stopping a hydraulic The valve 01 is a standard distributing valve motor in any predetermined Position of moveand is adapted, in one position, to interconnect ment without the use of blocks or similar positive the conduits n end is hil simultaneously in- D meimfiterconnecting the conduits it and 22 whereby It is anothe j t f t i invention to ressure iluid is delivered to the main area i: p h the above result Without r e of the plunger while the retraction area it is duly high pressures within the hydraulic system 85 e u t The valve i1 is also adapted to efsssocisted h the hydraulic motor. i'ect fluid communication betwen the conduits hese a d Ot er J 'O S Will become more II and I! while simultaneously interconnecting parent upon reference to the following descripthe conduits 1; d :2 thereby to deliver prestion taken inconnection with the attached drawsure fluid t th etraction area it while exn s in which! 40 hausting the main or advancing area l2.

Fi ure 1 is a dia rammatic v ew of a v ul c The conduit it includes a valve 25 which normotor and circuit therefor provided with the ram n permits free now in either direction th halting means Of th s nven and through but which is by-passed by a check valve Fi ure 2 s a vi w, of the P u generator zt'ror permitting fluid flow from the valve i1 emplflyed in this Quit and fitted with various 46 to the retraction area II but not vice-verse. this o t ls according t t s i v ntio and valve being provided for a reason which will be- Figure 31 is a section through a spring loaded come apparent hereinafter, valve constructed according to this invention. The valve m particularly Shown in Figure 3, comprises a casing having a shouldered General arrangement axial bore therein as at ii. the shoulder forming According to this invention, a fluid operable a valve seat as at 32. Reciprocably mounted in motor such as a vertically acting reciprocating the bore ii is a valve member 33 which is adapt: type motor is supplied with pressure fluid fromed to be moved downwardly into engagement a fluid source of variable delivery, The fluid with the seat 32 thereby to interrupt the fluid source may be directly connected to the opposite connection between the portions of the conduit areas of the reciprocating ram thereby to rei9 entering on opposite sides of the valve casing. ciprocate the same or may be connected through The valve member 33 is rigidly attached to or a reversing valve with the said ram. is integral with a rod II which terminates, at

The fluid source is preferably urged toward its upper end in an enlarged portion it which is full stroke position by a yielding means and in- 00 stopped, in its upward movement by the threaded plug '35 bears between piston 54 In operation,

3 31. A yielding means such as the spring the underside of the enlarged portion 35 and a portion of the casing 35 and serves to urge valve member 33 into their extreme upward position thereby normally to maintain a free fluid flow through the valve.

Referring again to Figure 1, it will be seen that the rod 35 extends downwardly from the valve 25 and has afilxed thereto, near its lower end, a collar 45. Resting on the collar 45 is a spring 4| which supports a second collar 42 which latter is slidable on the rod 35. An arm 43 is attached to the platen and encircles the rod 35 and is slidable thereover. This arrangement is such that, at a predetermined point of forward travel of the plunger II, the arm 43 will engage the collar 42 and, through the spring 4|, the collar 45 andthe rod 35 move the valve member 33 against the seat 32 and thereby efl'ect interrup tion of the fluid flow through the conduit l3..

The construction of the pump I5 is 'more particularly shown in Figure 2 where it will be seen to comprise a casing 55 within which is'm'ounted a movable flow control member 5|. .Attached to the left side of the casing '55 isan adjustable yielding means for continuously urging'the flow? control member 5| toward maximum delivery position. The yielding means comprises a pair of telescoping-cylinders 52 and.53, the former being provided with a slot 54 and the latter with a pin 55, these last mentioned means preventing rela-- tive rotation between the cylinders 52 and 53. A spring 55 is mounted within the cylinders and bears against one end of the cylinder 52 and the opposite end of the cylinder 53. A rod 55 is threadedly attached to the how controlmember 5| and extends through the centerof the spring 55 and through the end wall of the cylinder 53. The end of the rod 55 which extends through the end wall of the cylinder 53 is threaded and has associated therewith a hand wheel 51 which abutsthe outer portion of the cylinder 53. The vhand wheel 51 is effective, when moved, to adjust the thrust with which the spring 55 urges the cylinder 53, rod 55 and flow control member 5| toward the left or maximum delivery position.

; Attached to the opposite side of the flow control member 5| from the rod 55 is a-rod 50 which extends through the casing 55 into a. pair of cylinders 5|, 52. Attached to the rod 55 within the cylinder 5| is a piston 53 and within the cylinder 52 a piston 54. A conduit 55 leads'from the left end of the cylinder 52 to the discharge conduit i5 of the pump l5 while a conduit 55 leads from theleft end of the cylinder 5| to the conduit l9 at, a point between the cylinder in and the valve 30. It will be noted that the efiective area of the piston 53 is larger than the 'eifective area of the and that, therefore, a greater pressure is required to be introduced into the cylinder 52 through the conduit 55 in order toshift the flow control member toward neutral against the thrust ofthe spring 55 than is required to be introduced into the cylinder 5| to accomplish the same result.

Operation a working or downward stroke of the plunger Ii is instituted by shifting the valve "to interconnect the conduits l5 and I5 and the conduits l5 and 22. With the valve so shifted pressure fluid is delivered from-the pump i5 to the main area l2 while the retraction area I3 is exhausted through the conduit l5 and valves 25 and i1 and conduit to the reservoir 25.

downwardly the portion 35, the rod 35 and the "4 The plunger under these conditions, moves downwardly into work engaging position and thereaiter performs such work as it is desired to do. At the completion of the working stroke the valve I1 is shifted so as to interconnect the conduits l5 and I3 and the conduits I 3 and 22. The

' matic linkage or by manually shifting the valve pump now delivers pressure fluid through the conduit l9 to the retraction area i3 while the advancing area i2 is exhausted through the conduit l3, valve l1 and conduit 22 to the reservoir; The upward movement of the press platen may be stopped in any desirable manner, say, by autoto a neutral position.

If, at the completion of the working stroke, it is desired to maintain the press ram in engagement with the work under a predeter'minedpressure, the piston-cylinder 54, 52 is effective to accomplish this by moving the pump substantially to neutral in response to the pressure conducted thereto by conduit 55. Subsequent to thisv pressure dwell the valve l'l may be shifted to institute the retraction stroke.

If, however, on the downward stroke of the plunger l l the same advances beyond the maximum desirable oint of travel, the plunger will be brought to a halt in the following manner: the collar 40 on the rod 35 is adjusted so'that the platen arm 43 engages the collar 42 and moves the same downwardly to compress the spring 4| and thereby to close the valve 25 when the aforementioned maximum point of travel has been attained. When the valve 25 is closed, that is, when the rod 35 has moved'the valve member 33 downwardly into engagement with the seat 32 against the thrust of the spring 38, the passage of fluid through the conduit I9 is interrupted and the fluid remaining in the lower side of the cylinder ill is trapped. With the fluid beneath the plunger ll trapped, further movement downwardly of'the said plunger is effective tocreate a pressure in the said trapped fluidwhich is conducted, by means of the conduit 55, to the cylinder 5| where it acts on the piston 53 to urge the flow control member of the pump toward neutral. It will be apparent that the pressure required to move the pump to neutral or no delivery position under these circumstances is less than the pressure required to move the pump to neutral when the ram is dwelling on the work as explained hereinbefore. It will also be evident that, since the retraction area I3 is considerably smaller than the advancing area l2, the pressure on the advancing area and, therefore, in the pump discharge conduit will be even smaller than the pressure developed in the lower end oi the cylinder iii. For example, if the advancing area is retraction stroke of the ram may be instituted by shifting the valve l'l so as to direct the pump discharge into conduit I9 while simultaneously exhausting the advancing area through the conduit i8, valve l1 and conduit 22 to the reservoir. At this time, the discharge of the pump flows through conduit I5, valve l1 and conduit l9 to the check valve 25 and passes therethrough to the retraction area l3. The valve 25 is thus bypassed and the fact that the same is closed has no effect whatsoever on the normal retraction stroke of the ram.

It will be apparent that various modifications are possiblein the structure and arrangement thereof without in any way departing from the spirit of the invention. For example, the pump i5 could be of the reversible variable delivery type and be connected directly to the advancing and retracting areas thereby eliminating the reversing valve l1.

, Accordingly, it will be understood that I do not wish to be limited to the specific structure and arrangement shown in the drawings but desire to comprehend such modifications thereof as come within the scope of the claims.

Having thus fully described my invention what I claim as new and desire to secure by Letters Patent, is:

1. In a hydraulic system, a downwardly acting fluid .operable plunger having associated therewith a larger advancing area and a smaller retraction area, a variable delivery pump connected to supply actuating fluid to said areas for reciprocating said plunger, a first valve selectively operable for directing the flowof fluid from said pump to said advancing area or to said retraction area while simultaneously exhausting the other of said areas, a second valve arranged between said retraction area and said first valve and including a valve member movable to interrupt fluid communication between said retraction area and said first valve, yielding means associated with said valve member for continuously urging the same into position to permit fluid communication between said retraction area and said first valve, a rod attached to said valve member, a collar adjustably attached to said rod, a spring on said rod and supported by said collar, an arm associated with said plunger and adapted in response to a predetermined advancing movement thereof to engage said spring and therethrough to urge said collar, said rod and said valve member against the thrust of said yielding means into position for said valve member to interrupt fluid communication between said retraction area and said flrst valve, a fluid operable servomotor associated with said pump and hydraulically connected with said retraction area and operable in response to the pressure created thereby by the advancing movement of said plunger immediately subsequent to the closing of said second valve to move said pump into substantially no delivery position thereby to halt said plunger, and means associated with said second valve and operable to permit the flow of fluid from said first valve to said retraction area so as to permit the initiation of a retraction stroke when said second valve is closed.

2. In a hydraulic system, a reciprocable ram means having a larger advancing area and a smaller retraction area, a variable delivery pump for supplying actuating fluid to said areas for reciprocating the ram, a reversing means, said reversing means being selectively operable to direct the discharge or the pump to the advancing area or to the retraction area while simultaneously connecting the other oi. said areas to exhaust, a first fluid operable servomotor associated with said pump and having an eflective area hydraulically connected with the outlet of said pump and operable in response to a predetermined pressure therein to move said pump into substantially no delivery position, a second fluid operable servomotor associated with said pump and having an efiective area substantially larger than that of said first servomotor hydraulically connected with said retractionarea and operable in response to a predetermined pressure therein substantially smaller than the first mentioned predetermined pressure to move said pump into substantially no delivery position, a valve hydraulically connected with said retraction area and said reversing means and operable by said ram in response to a predetermined advancing movement thereof to interrupt the flow of fluid from said retraction area to said reversing means to create pressure in said retraction area, and means by-passing'said hydraulically connected valve for permitting the flow o1 fluid from said reversing means to said retraction area only.

3. In a hydraulic system, a reciprocable ram means having a larger advancing area and a smaller retraction area, a variable delivery pump for supplying actuating fluid to said areas for reciprocating the ram, a reversing means, said reversing means being selectively operable to direct the discharge of the pump to the advancing area or to the retraction area while simultaneously connecting the other of said areas to exhaust, a first fluid operable servomotor associated with said pump and having an effective area hydraulically connected with the outlet of said pump and operable in response to a predetermined pressure therein to move said pump into substantially no delivery position, a second fluid operable servomotor associated with said pump and having an effective area substantially larger than that of said first servomotor hydraulically connected with said retraction area and operable in response to a predetermined pressure therein substantially smaller than the first mentioned predetermined pressure to move said pump into substantially no delivery position, a valve hydraulivalve in said conduit.

cally connected with said retraction area and said reversing means and operable by said ram in response to a predetermined advancing movement thereof to interrupt the flow of fluid from said retraction area to said reversing means to create pressure in said retraction area, and means by-passing said hydraulically connected valve for permitting the flow of fluid from said reversing means to said retraction area only, said by-passing means including a conduit which by-passes said hydraulically connected valve, and a check BERNARD D. ASI-BAUGH.

REFERENCES CITED The following references are of record in the file or this patent:

UNITED STATES PATENTS France Oct. 5. 1936 

